11.9.2.2 devinfo_t

The devinfo_t structure provides
information about a device. The devinfo_t
structure that corresponds to the destination device of an I/O
is pointed to by args[1] in the
start, done,
wait-start, and
wait-done probes. Detailed information
about this data structure can be found in
/usr/lib64/dtrace/version/io.d.
The definition of devinfo_t is as follows:

DTrace translates the members of
devinfo_t from the
buffer_head for the Oracle Linux I/O request
structure.

dev_major: Is the major number of the
device.

dev_minor: Is the minor number of the
device.

dev_name: Is the name of the device driver
that manages the device.

dev_statname: Is the name of the device as
reported by iostat. This field is provided
so that aberrant iostat output can be
quickly correlated to actual I/O activity.

dev_pathname: Is the full path of the
device. The path that is specified by
dev_pathname includes components expressing
the device node, the instance number, and the minor node.
However, note that all three of these elements are not
necessarily expressed in the statistics name. For some
devices, the statistics name consists of the device name and
the instance number. For other devices, the name consists of
the device name and the number of the minor node. As a result,
two devices that have the same dev_statname
migh differ in their dev_pathname.